Explore all exterior drainage options before making choice

Q. I am hoping you can provide some guidance for an issue at the house we now live in. This ranch house was built in 1979 and has a walkout/daylight lower level. We bought it as our "senior citizen" home and hope to stay here as long as possible.

We moved in May 2014. Immediately after, the problems began.

We have had numerous basement water issues on the lower level and had to remove 80 feet of drywall and floor coverings in the finished basement along the back wall that is below grade. We found mold, foundation cracks and bowing walls. A big mess. Long story short, the former owner denied knowing about any of this, and we ended up in mediation to resolve the matter.

We have stabilized the bowing walls with carbon fiber straps but now want to install a French drain outside along the front. The front yard gently slopes downward toward the house and of course the grading right in front of the house is at a low point. The landscaping will be fixed after the drain is installed.

Can you tell me the correct construction of the French drain and what materials you recommend? Should it extend down past the sides of the house? We are about to spend thousands of dollars on this project and want to make sure it is done correctly so we don't have to worry about it when we are in our 80s.

I appreciate any advice you have. I have tons of pictures that I could send you if they would help. We are speaking to the contractor soon and would like to know the correct construction.

A. If the slope of your front yard is as gentle as you say, you may be able to handle the water and snowmelt problem less expensively, and with less disturbance, than by building a French drain.

A swale can be shaped a few feet away from the front of the house that would intercept the water and lead it to either one or both sides of the house. The advantage of the swale is that it will also allow you to slope the grade from the house to the swale, something that is always essential to prevent foundation leakage. To accomplish this, the land above the swale will have to be regraded, and will have a steeper slope.

But if, after analyzing the situation, you determine that a French drain is the better approach, this is how it should be built:

A French drain consists of a trench dug a few feet away from a building's foundation, so as not to endanger it. The trench may need to be as deep as the house foundation if underground water is found to be oozing at that depth.

If the amount of water deemed to enter the French drain from the surface and below is unusually heavy, it may be desirable to line the side closest to the house with 6-mil black plastic to prevent water from the higher ground from percolating into the soil between the trench and the house foundation. (But omit the plastic if you determine that rain and snowmelt in the soil in the space between the house and the trench also need a place to drain.)

Remember that part of the excavation work must include sloping the ground from the foundation to the trench to direct surface water away from the house, just as in the case of a swale.

Lining the bare side(s) of the trench with filter fabric is advised to prevent eventual silting.

A Schedule 20 PVC perforated drainpipe is usually laid on the bottom of the trench over a couple of inches of egg-sized stones. The trench is then filled with the same type of stones to the very top of the trench, and left exposed.

This is what differentiates a French drain from a curtain drain. The stones in a curtain drain stop a foot or so from the top of the trench and, after being covered with landscape fabric, backfilling is made with soil, and grass is planted. Curtain drains are used if subsurface water is a problem, and if looking at the stones of a French drain is less than desirable. However, a curtain drain requires a swale to divert surface water away from the house.

A French drain (as well as a curtain drain) must have one or two outlets to drain it to daylight by means of a solid pipe that should extend to one or both sides of the house.

Q. We have a cedar-sided house. This past summer we had the house spray-washed and stained with two coats of Olympic cedar stain.

We recently had our first cold weather, and for the first time ever we have condensation on the inside of some windows. I talked with the contractor and he assured me that he had adequately caulked around all the windows.

There are, however, some small areas around the windows that are not caulked. The way the cedar boards lap over each other creates a small lip on the bottom edge of each board. (I hope this makes sense.) Each lip is about a quarter-inch wide. Some are caulked, while others are not.

Is it possible that these very small spots on the boards around the windows could be the cause of the condensation buildup? Could it be attributed to all the water that was sprayed onto the wood and it takes time to totally dry out? Or is it a combination of both - or maybe none of the above?

A. Did the power-washed siding dry completely before the stain was applied? It is always a good idea, after power-washing, to check the moisture content of the wood prior to applying any coating.

All experienced painting contractors should carry a moisture meter and check the surface in many places before starting a job. But I don't think this is entirely your problem, although it may contribute to it to a very minor degree.

It is more likely to be the fact that so much caulking was done, it sealed any exfiltration and infiltration paths your house may have had before the caulking and staining.

In houses that are not tightly built or made tighter with caulking and other means, upper-level exfiltration through various cracks and openings encourages infiltration on the lower level. This process exchanges the air and the house breathes.

Keep in mind also that all houses ventilated by open windows in the summer accumulate a considerable amount of moisture from the outside air. This moisture takes weeks to dissipate once the heat is turned on.

It is likely your house was not as tight before the caulking, which helped prevent condensation on the windows.

This is not to imply that you should not have improved the energy efficiency of your house; it simply means you need to ventilate the house. This can be done by opening windows in mild temperatures or by mechanically ventilating it by using bathroom and kitchen fans until the relative humidity (RH) is considerably reduced. You will need to provide an air intake, such as a slightly opened basement window, etc., for this to be effective.

Another option is to have an air-to-air heat exchanger installed. You may also look into your lifestyle and see if you can reduce the RH by eliminating some moisture sources.

Q. Our home is 11 years old, and we live just south of Pittsburgh, Pennsylvania. Our basement has flooded quite a few times. Multiple factors caused the flooding, but we believe that problem has been solved.

The issue I now need help with is a west-facing, underground basement wall. It has possible mold damage. I scrubbed it three times with a 50/50 bleach/water mixture. Some of the areas lightened up, but the spots are still there.

When I asked an employee at our local home improvement store, he advised removing the original paint, then using hydraulic cement, then repainting the wall. Is this information correct? If so, how do you suggest removing the paint? Is there any other option that might be easier, yet as effective? I have enclosed pictures of the interior wall as well as pictures of what is on the outside of this wall. Any advice you can suggest would be greatly appreciated.

A. The only reason to use hydraulic cement is to fill holes through which water gets in. I don't see that on your photos.

Since I do not see any paint peeling, my guess is that the block wall was painted with a cementitious paint. If that is the case, the coating can probably be removed using Peel Away 4 Cementitious Coating Removal System. Peel Away 4 works on most masonry coatings. You should be able to get it in well-equipped and experienced paint stores, but if they don't carry it in stock, they should be able to order it for you. Otherwise, you can buy Peel Away 4 online at www.dumondchemicals.com.

However, removing the coating may not get rid of the stains. Your photos show what look like rust spots and not mildew, which the bleach treatment should have removed. If you are certain the moisture problem has been solved, you might try Bulls Eye 1-2-3 Plus applied over the existing coating. It should hide the rust stains. If you don't notice any peeling or other problems after a few months, you can then paint the walls with any top-quality latex paint.

If that does not work, use Peel Away 4 and start all over.

• Henri de Marne was a remodeling contractor in Washington, D.C., for many years, and is now a consultant. His book, "About the House," is available at www.upperaccess.com. His website is www.henridemarne.com. Email questions to henridemarne@gmavt.net, or mail First Aid for the Ailing House, Universal Uclick, 1130 Walnut St., Kansas City, MO 64106.

© 2016, United Feature Syndicate Inc.